Numerous grease extraction ventilators have been developed, including those utilizing a water bath or water spray to assist in the removal of grease, smoke and the like, from heated air and products of cooking, as well as a dry type, in which heated air and products of cooking are passed through a body of mesh, such as retained between two screens. Normally, the bonnet or hood of a grease extraction ventilator comprises a series of depending walls which essentially surround an enclosure which is placed above the cooking equipment, so that heated air and products of cooking, rising from the cooking equipment, will collect in the bonnet and will flow toward the grease removal portion of the ventilator, then into a duct which extends to an exhaust fan or blower for exhausting the remaining air and gases, such as into the atmosphere. The exhaust fan produces a suction in the duct and draws the air and products of cooking through the grease removal means, which also may condense water vapor and remove small particles. All such ventilators have the problem, at times, of being flooded with smoke, as when a fire occurs, particularly on a broiler or other type of cooking equipment operating at higher temperatures. Normally, room air is drawn under the walls which surround the enclosure, which walls are normally the front and end walls, since the usual installation of a grease extraction ventilator is against a wall of a kitchen. However, there are some ventilators which have four walls exposed to the room and the method and device of this invention are equally applicable to such ventilators.
When an abnormal amount of smoke is produced, the smoke may tend to curl or roll underneath the lower edges of the enclosure walls and penetrate into the room. Often, such smoke carries cooking odors with it and may find its way into the dining area, which is often adjacent the kitchen, and become not only visually but also olfactorily disagreeable to the patrons. As far as is known, no success has met with attempts which have been made to cure this problem.
Among the objects of this invention are to provide a method of retarding or preventing the curling or rollout of smoke from beneath the edges of the depending walls which form an enclosure for receiving the products of cooking as well as room air; to provide such a method which is effective and efficient in overcoming this problem; to provide such a method which may be carried out with a minimum of expense; to provide a device which is particularly adapted to carry out the method of this invention; and to provide such a device which is readily and inexpensively incorporated in a grease extraction ventilator.